The present invention relates to an electophotographic copier, laser printer, facsimile apparatus or similar image forming apparatus and, more particularly, to an image forming apparatus capable of forming a plurality of images in separate areas of an intermediate transfer body.
It is a common practice with an electrophotographic image forming apparatus to transfer a toner image from a photoconductive element to a paper or similar recording medium and then fix the toner image on the paper. In another image forming apparatus known in the art, the toner image is transferred from the photoconductive element to the paper by way of an intermediate transfer body. Assume that the image forming apparatus of the type including the intermediate image transfer body is operated with papers whose size is less than one half of the maximum paper size available with the apparatus. Then, a plurality of toner images may be transferred to separate areas of the transfer body and then sequentially transferred to consecutive papers in order to increase the continuous processing speed, as taught in, e.g., Japanese Patent Laid-Open Publication No. 7-72701. This document additionally discusses various timings for turning on cleaning means assigned to the transfer body in the event of the above continuous transfer of the toner images to consecutive papers.
So long as papers are sequentially fed in synchronism with the toner images transferred to the intermediate transfer body, the above conventional method for cleaning the intermediate body is successful. However, even when papers are absent, the next toner image is formed on the photoconductive element or image carrier. In this case, the amount of toner constituting the toner image is too great to be fully removed by the usual ability of the cleaning means. Toner left on the intermediate body would be added to toner to be transferred from the image carrier to the transfer body at the next image forming procedure, resulting in a defective image.